This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A160126 #13 Feb 24 2021 02:48:18 %S A160126 0,0,0,1,2,2,4,9,12,12,14,18,20,22,32,47,54,54,56,60,62,64,74,88,94, %T A160126 96,104,114,120,134,170,209,224,224,226,230,232,234,244,258,264,266, %U A160126 274,284,290,304,340,378,392,394,402,412,418,432,466,500,514 %N A160126 Total number of squares and rectangles in the toothpick structure after n stages, divided by 2. (See A139250). %H A160126 David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="/A000695/a000695_1.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>, Congressus Numerantium, Vol. 206 (2010), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-1) for n >= 2.] %H A160126 N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a> %F A160126 a(n) = A160124(n)/2. - _Nathaniel Johnston_, Apr 12 2011 %Y A160126 Cf. A139250, A159786, A159787, A159788, A159789, A160124, A160125, A160127. %K A160126 nonn %O A160126 0,5 %A A160126 _Omar E. Pol_, May 03 2009 %E A160126 Terms beyond a(10) from _Nathaniel Johnston_, Apr 12 2011